It is desirable to adjust the color of lighting systems utilizing point light sources, including light-emitting diodes (LEDs), metal halide light sources, and ultraviolet light sources, for general and task illumination on a widespread basis. However, a problem with many point light sources is that the available visible color spectrum of light produced by the point light sources is limited. For instance, LEDs are available only in limited colors. Therefore, in commonly assigned U.S. Pat. No. 7,011,421, and in commonly assigned and co-pending U.S. patent application Ser. No. 11/025,019, each of which is incorporated in its entirety herein by this reference, illumination devices are described that use fluorescent and/or phosphorescent dyes, thus allowing for emission of light in colors that cannot ordinarily be achieved by use of LEDs alone without a significant increase in cost or complexity of the illumination device. However, it is desirable to be able to easily adjust the color of the light emitted by such illumination devices.